Surgical repair of intracardiac defects with pulmonary hypertension is still associated with a 20 to 30 percent mortality, often secondary to right ventricular dilatation and failure. Unloading of the right ventricle may be accomplished by venous unloading only at the expense of left ventricular output. Therefore we are evaluating a unidirectional intra-atrial flap valve that allows right-to-left shunts when right ventricular filling pressures are elevated, thus decompressing the right ventricle while maintaining or improving left ventricular output.